How a tornado showed me that Twitter has permanence

FORTUNE — On April 28, a tornado spun through my girlfriend’s hometown, Tupelo, Mississippi, where most of her family and friends still live. The first news was very bad. Her grandfather’s house was missing a bedroom. An uncle’s house had no roof. And the system of storms hadn’t passed. As she texted with friends and family, many of whom were still sheltering in their basements, they tried to ascertain whether the funnel was still on the ground, and where. “Hand over your iPad,” she demanded. “I need your Twitter account.”

That evening, my girlfriend, who had never been a Twitter TWTR user, hit the refresh button on my account over and over again. While the local weather affiliate was forced off-air and a power outage prevented folks from checking the news, she texted out Twitter updates and watched — or, more accurately, read about — the tornado as it made its way through the nearby city of Jackson. She told her friends there to please stay inside because it had just touched down near Interstate 20. As the emergency subsided, she logged out of my Twitter account and started her own.

Twitter has had a rough couple of weeks. After admitting in its first quarter 2014 earnings that user growth had slowed, the price of its shares dropped. Sure, Twitter had added 14 million users for a total of 255 million users, but they seem to be reading their feeds less than they had been a year earlier. The Atlantic published a widely shared eulogy for the service that can best be summed up as, “it’s not fun anymore.” Then a week later, when an early employee lock-up expired, its stock dropped again. Twitter is now trading at around $33, down from a $73 high in December.

Don’t be fooled, though — Twitter is not in trouble. And it hasn’t lost its influence, as The Atlantic suggests. There are a core group of social media news types who once provided great benefit to Twitter because they tested the platform early, wrote about it a ton, and fell in love with it before it became mainstream. Some of them are now souring on it, having tired of the communities they once sought. (To quote The Atlantic:“Too much of Twitter was cruel and petty and fake.”) But even if they leave it, I predict these Twitter users will come back as soon as something truly important happens in the world. They’ll pull up Twitter at the same time as they turn on the TV, maybe sooner. Twitter has firmly established itself as the global 9-1-1 as well as a faster, more local CNN, a place to call for help and shout the news — a place people where people flock when they need to know things fast.

And there is no real competition for this role. In Tupelo on April 28, the local weather channel correspondent ran for shelter while on the air. TV stations didn’t have the ability to answer viewers’ questions in realtime, and they rarely knew the answers. Instagram proved visually arresting, but less effective as a messaging tool. The electricity was out, phones were down, but for those who had a bit of battery left on their devices, Twitter surfaced a steady stream of tweets tracking the storm’s progress.

As artificial intelligence and predictive technologies improve, this service will be of greater commercial value. The New York-based data analytics startup Dataminr offers an early example of this. With nearly $50 million in funding, the company sifts through tweets to identify newsworthy events. In March, when a gas explosion decimated a section of a Harlem city block, Dataminr confirmed the event had occurred within 200 seconds; it took local news stations 20 minutes to cover it. Because the startup excels at pattern recognition, it can quickly verify which information is accurate — and which, like the hacked Associated Press Twitter account that broadcasted two explosions in the White House, is a hoax. “We knew the AP had been hacked,” Dataminr CEO Ted Bailey told me during a recent visit to Fortune‘s New York offices. “All the signals around how the news broke were exactly the opposite of what they should be.” Bailey is working with CNN and Twitter directly to pilot a new product that will help journalists mine Twitter more effectively for breaking news, and insight into how it spreads.

This will be important to my girlfriend, anxious to insure that her family members are safe, but it will also be important to anyone who relies on realtime news. Bailey says Dataminr has already signed 50 clients in financial services, most of which will use the early insight to play the market. No doubt, it’s problematic that Twitter’s users are spending less time on the platform, a fact Twitter CEO Dick Costolo blames on new product changes. Twitter must innovate on its product to keep it top of mind for current users and to make it easier for new users to engage. But the service is best understood as one that successfully tackles a niche, rather than trying to do anything. Twitter has become our global emergency information system. Because the ability to access and share realtime information in the moments that a tornado is on the ground is invaluable for people like my girlfriend, she won’t abandon her Twitter account, even if she doesn’t use it for a very longtime. Because companies that rely on realtime news care most about new events, their businesses won’t suffer if my girlfriend isn’t tweeting or digesting her newsfeed in the interim.

Oh, and her family in Tupelo? They’re all okay, though many of their houses are not. A security camera at a local church caught the tornado itself in a video that is not to be missed — the trees tumble like dominoes. And a local company created a web site called Tupelo Strong where people can crowdsource resources to help each other out. It’s worth tweeting.